How to prevent a criminal government in taking part in Democracy?

In the interest of the common people, for whom and by whom is a Democracy made, IT IS NECESSARY THAT ANY ONE WITH EVEN A SMALL CRIMINAL PROCEEDINGS AGAINST HIM/ HER SHOULD NOT (NOT...NOT...NOT) BE ALLOWED TO STAND FOR ELECTION. Unless such stringent NORMS are followed, people like Lalu Prasad, Shibu Soren would hijack Democracy into their own home backyards, and even Directors of the IIM's would become thier "chamchas"...as is unfortunately happening.